Regulation of plant gene expression by tsRNAs in response to abiotic stress.

Objective: Transfer RNA-derived small RNAs (tsRNAs) are emerging regulators of gene expression in response to abiotic stress. This review aims to summarize recent advances in the classification, biogenesis, and biological functions of tsRNAs, with a focus on their roles in plant stress responses and the methodologies for investigating these molecules.

Methods: We conducted a comprehensive literature search across PubMed, Web of Science, and Google Scholar using keywords such as "tRNA-derived small RNAs", "abiotic stress", "plant gene regulation", and "RNA sequencing". Studies were selected based on their relevance to tsRNA biogenesis pathways, stress-responsive mechanisms, and functional validation in plant systems. Classification of tsRNAs was performed according to cleavage site specificity and nucleotide length. Bioinformatic tools and experimental approaches for tsRNA identification, target prediction, and functional validation were evaluated.

Results: tsRNAs are categorized into two main types: tRNA-derived stress-induced RNAs (tiRNAs; 29-50 nt) and tRNA-derived fragments (tRFs; 14-40 nt). tiRNAs arise from anticodon loop cleavage by RNase A/T2, while tRFs are generated via Dicer-dependent or -independent pathways. These molecules regulate gene expression at transcriptional, post-transcriptional, and translational levels by interacting with AGO proteins, displacing translation initiation factors, and modulating stress granule assembly. In plants, tsRNAs respond dynamically to abiotic stresses (e.g., drought, salinity, heat), influencing stress signaling pathways and epigenetic modifications. Advanced sequencing techniques (e.g., cP-RNA-seq, RtcB sRNA-seq) and databases (PtRFdb, tRFanalyzer) have facilitated tsRNA discovery and functional annotation.

Conclusions: tsRNAs represent a versatile class of regulatory molecules in plant stress biology. Their ability to fine-tune gene expression underpins adaptive responses to environmental challenges. Future research should prioritize standardized methodologies for tsRNA profiling, elucidation of stress-specific biogenesis mechanisms, and exploration of their potential as biomarkers or therapeutic targets for crop improvement. Integrating tsRNA research with systems biology approaches will deepen our understanding of plant resilience mechanisms.